I. Field of the Invention
The present invention relates generally to the manufacture of propellant charge systems for large caliber artillery pieces, more particularly, to modular artillery charge systems or MACS, and involves improvements in a load, assembly and packaging process for manufacturing field modular charge units for singular and multi-unit propellant charge systems. Specifically, the invention is directed to an improved solvent application system and method which coordinates the sealing of the lid to the case of a MACS unit with precision.
II. Related Art
Propellant charges for cannon artillery systems, primarily large caliber weapons systems such as 155 mm howitzers, etc., typically include plurality of coordinating modular charge units serially loaded behind the shell. The individual modular charge units are generally cylindrical in shape, frequently having a length to diameter ratio approaching 1. A central axial opening is provided through each unit to facilitate ignition of that and consecutive units. Such a system concept is illustrated, for example, by Reinelt, et al., in U.S. Pat. No. 4,702,167.
Particular embodiments of such modular units are of a three-piece design, which includes a combustible case body, normally nitrocellulose, having a closed end provided with a central bore opening and an open end, a combustible cap or lid, provided with a central bore opening that aligns with that of the case body is adapted to fit or nest in and seal into the open end of the case body, and a combustible central or core tube, which fits over raised rims in the central bores of and connects the central openings provided in the closed ends of both the relatively rigid case body and lid to form a continuous central bore for containing core igniter bags. Top and bottom recesses are provided to accommodate two end igniter bags. This assures proper ignition of a number of serially placed modular charges. Up to eight modular charges may be employed in firing a 155 mm howitzer, for example.
The MACS load, assembly and packing process utilizes a series of discreet work stations, each of which is designed to accomplish a specific operation on the case, charge or additive materials. The present invention deals primarily with the provision of a significantly better approach to one difficult manual portion of the process including an operation at one discrete station in which the peripheral interface between the case and lid is sealed by the application of a volatile solvent such as acetone for the case and lid material.
This operation requires a specified, metered amount of solvent, normally acetone, to be applied evenly along the joint between the nitrocellulose case body and lid. Upon application, capillary action between the two rather tight fitting pieces draws the acetone along the mating surfaces and produces fusing of the two components together thereby sealing the module. The step further requires a positive shut-off from the solvent to prevent solvent spills and contact with the part other than at the juncture to be sealed. This step of the process has heretofore been accomplished entirely by a hand operation, the consistency of the results resting on the repetitive skill of the individual operator. The operator applied the acetone or other solvent using a hand-held syringe while, at the same time, spinning the module on a turn table. The operation of the table was also controlled by hand. This led to many peripheral inconsistencies in the form of over application and gaps in the application of the acetone, solvent and/or so to inconsistent sealing of the module. The syringe often would leak solvent onto the module rather than stopping abruptly at the end of the step. These drawbacks, in turn, could lead to rejection of the unit. This situation speaks of a definite need to improve this step of the process, to increase the accuracy of the sealing of the case and lid of each module, and also to remove the burden of consistency from the individual operator.
Accordingly, it is a primary object of the present invention to provide a system that automatically rotates and seals the case body and lid in a modular artillery charge system.
It is a further object of the present invention to provide such a fixture that is capable of consistently metering the exact desired amount of solvent and of insuring a complete solvent shut-off thereafter.
A still further object of the present invention is to provide such a system which interlocks the operation of the solvent dispensing with the rotation of the modular unit.
Another object of the present invention is the provision of a mechanized processing station that interlocks solvent dispensing with the provision of proper ventilation.
Still another object of the present invention is to provide a mechanized processing station that includes a mechanized turn table and adjacent solvent application device that assures complete and proper sealing of the module.
Additional objects and advantages regarding the invention will become apparent to those skilled in the art upon familiarization with the specification, drawings and claims contained herein.
The present invention solves many problems associated with the prior existing processes by providing automated mechanized discreet workstation system for precisely applying sealing solvent to the lid/body interface of a modular artillery charge system (MACS) unit or other workpiece. This system provides for case rotation and automated precise solvent quantity metering and shut off. Distribution (placement) about the periphery of the interface is also uniform as application is coordinated with turn table rotation.
The system is pneumatically-operated and includes a pneumatically driven turn table for mounting and rotating the modular unit to be sealed which is situated in precise relation to a solvent dispensing valve which applies the desired amount of solvent about the circular juncture between the cap and body as the modular unit is rotated. The solvent, normally acetone for a nitrocellulose cap and body, by capillary action is drawn into the joint to provide a complete welded or fused nitrocellulase seal.
The solvent dispensing system is contained on a mounting table beneath a ventilation hood and its operation is interlocked with a ventilation fan in the hood. The solvent dispensing system includes a solvent supply tank and a solvent supply dispensing valve which cooperates with a gas-tight measuring syringe connected also to a solvent dispensing valve. The solvent is precisely loaded and discharged by the operation of the measuring syringe. The syringe plunger is operated by a double acting hydraulic cylinder operated by a pair of air over metered fluid supply containers which cooperate with a follower arm-operated limit valve. A precise sequencing control system is also provided to coordinate proper sequencing of dispensing and refilling operations.
After a startup timing sequence, the operation is initiated by the operator utilizing a foot valve, or the like, and proceeds thereafter automatically to seal a modular unit placed in the turn table and then precisely reload the gas-tight measuring syringe for the next unit in a manner which is controlled by time-interlocked pneumatic valves and electric relays. Thus, the system and method of the invention for the precise patterned application of a liquid material upon a moving workpiece.